The present invention relates to a memory card storing personal data etc., which provides security against forging or altering the card, or relates to an image-recording medium, a method and apparatus for reading data, which is desirably suited for passports, etc.
Recently, in the field of service industries such as, for instance, banks, companies, schools, government offices, etc., electronic cards or magnetic cards of contact type or non-contact type have proliferated widely. Various kinds of data are recorded on cards utilized in the abovementioned fields, such as cash-cards, employee identification cards, company staff identification cards, membership cards, student identification cards, certificates of alien registration, various kinds of license cards, passports, etc. In addition, a security processing is applied for such cards, not to be easily forged or altered.
For instance, a special image is formed in a hologram-layer fabricated on the card substrate to prevent a portrait image, a name, an issue date, etc., from being easily imitated. This special image is formed as an optical variable image, which is generally called as a holographic image or a diffraction grating image. A holographic image is formed by interference fringes, which are generated by overlapping a light-wave, reflected or transmitted from the subject, with a reference light-wave. A virtual three-dimensional image can be reconstructed by means of such holographic image. A protective sheet, made of a transparent resin such as a laminate, etc., covers the hologram-layer, which is less wear resistant than the card substrate.
Although the information bearing layer and the hologram-layer are fabricated on the card substrate, as mentioned above, there is a possibility that reading errors of the information could occur due to duplication of the holographic image and the information, when an optical reading apparatus reads the information by means of reflected light at sites such as, for instance, an admission place for shopping, passing or entrances.
To overcome the abovementioned drawbacks in conventional image-recording media, it is an object of the present invention to provide an image-recording medium, an information-reading apparatus and an image-reading method, which make it possible to improve reading accuracy of information by avoiding duplication of an optical variable image with the information.
Accordingly, to overcome the cited shortcomings, the abovementioned object of the present invention can be attained by image-recording media and an image reading methods described as follow.
(1) An image-recording medium, comprising a substrate, an image-receiving layer provided on the substrate and an optical variable layer provided on the substrate, wherein at least a part of the optical variable layer comprises an optical variable image, and the optical variable image is formed in a manner such that the optical variable image, overlapping with an image recorded on the image-receiving layer, emerges in a first direction, while the optical variable image, overlapping with an image recorded on the image-receiving layer, does not emerge in a second direction.
(2) The image-recording medium of item 1, wherein the optical variable image is formed on information recorded on the image-receiving layer.
(3) The image-recording medium of item 1, wherein both a first optical variable image and a second optical variable image are formed in the optical variable layer, a viewing angle of the first optical variable image is different from that of second optical variable image.
(4) The image-recording medium of item 3, wherein the second optical variable image is formed on at least a part of characters recorded on the image-receiving layer.
(5) The image-recording medium of item 1, wherein an optical variable image is formed on at least a part of characters recorded on the image-receiving layer so as to overlap with the characters, and the following equation is fulfilled,
0.3xe2x89xa6(Moxe2x88x92Mx)/Mxxe2x80x83xe2x80x83(1)
where: Mx; the reflectance at a point, at which the characters are formed under the optical variable image, Mo; the reflectance at a point, at which the characters are not formed under the optical variable image.
(6) A method for reading information from an image-recording medium, which comprises a substrate, an image-receiving layer provided on the substrate to record the information in it and an optical variable layer provided on the substrate, comprising steps of irradiating a light onto the image-recording medium and reading a reflected light form a second direction, wherein at least a part of the optical variable layer comprises an optical variable image, and the optical variable image is formed in a manner such that the optical variable image, overlapping with an image recorded on the image-receiving layer, emerges in a first direction, while the optical variable image, overlapping with an image recorded on the image-receiving layer, does not emerge in the second direction.
(7) A method for reading information from an image-recording medium, which comprises a substrate, an image-receiving layer provided on the substrate to record the information in it and an optical variable layer provided on the substrate, comprising steps of irradiating a light onto the image-recording medium and reading a reflected light, wherein an optical variable image is formed in at least a part of the optical variable layer, and in the step of reading a reflected light, the reflected light having a wavelength other than a wavelength of the optical variable image is read.
(8) A method for reading information from an image-recording medium, which comprises a substrate, an image-receiving layer provided on the substrate to record the information in it and an optical variable layer provided on the substrate, comprising steps of irradiating a light onto the image-recording medium and reading a reflected light, wherein an optical variable image is formed in at least a part of the optical variable layer, and in the step of reading a reflected light, the reflected light is read from an angle other than a viewing angle of the optical variable image.
Further, to overcome the abovementioned problems, other image recording media, information-reading apparatus and image-reading methods, embodied in the present invention, will be described as follow:
(9) An image-recording medium, characterized in that, in the image-recording medium in which an optical variable layer and an image-receiving layer are successively overlaid with a card substrate and comprises information in the image-receiving layer, the optical variable layer is structured in such a manner that the optical reading apparatus can read only the information by receiving the reflected light in the predetermined direction, in which no optical variable images, overlapping with the information, emerge on the image-recording medium.
According to the image-recording medium described in item 9, accuracy for reading the information will be improved, since no optical variable images, overlapped with information, emerge on the image-recording medium, when reading the information from the predetermined direction by using the reflected light.
(10) An information-reading apparatus, characterized in that the image-recording medium, in which an optical variable layer and an image-receiving layer are successively overlaid with a card substrate, comprises the optical variable layer, which is structured in such a manner that the information-reading apparatus can read the information by using the reflected light, and the information-reading apparatus comprises a reading section to only read the information of the image-recording medium by receiving the reflected light in a predetermined direction, in which no optical variable images, overlapped with the information, emerge.
According to the information-reading apparatus described in item 10, accuracy for reading the information will be improved, since no optical variable images, overlapped with information, emerge on the image-recording medium, when reading the information from the predetermined direction by using the reflected light.
(11) The information-reading apparatus described in item 10, characterized in that the information-reading apparatus reads the information by relatively moving the image-recording medium and the reading section in the predetermined direction.
According to the information-reading apparatus described in item 11, accuracy for reading the information will be improved, since no optical variable images, overlapped with the information, emerge on the image-recording medium, when reading the information by relatively moving the image-recording medium and the reading section in the predetermined direction.
(12) An information-reading method, characterized in that the image-recording medium, in which an optical variable layer and an image-receiving layer are successively overlaid with a card substrate, comprises the optical variable layer, which is structured in such a manner that an information-reading apparatus can read the information by using the reflected light, and a reading section of the information-reading apparatus reads the information of the image-recording medium by receiving the reflected light in a predetermined direction, in which no optical variable images, overlapped with the information, emerge.
According to the information-reading method described in item 12, accuracy for reading the information will be improved, since no optical variable images, overlapped with information, emerge on the image-recording medium, when reading the information from the predetermined direction by using the reflected light.
(13) The information-reading method described in item 12, characterized in that the information-reading apparatus reads the information by relatively moving the image-recording medium and the reading section in the predetermined direction.
According to the information-reading method described in item 13, accuracy for reading the information will be improved, since no optical variable images, overlapped with the information, emerge on the image-recording medium, when reading the information by relatively moving the image-recording medium and the reading section in the predetermined direction.